LG B2050 Service Manual - Page 78
Checking Flow, CIRCUIT DIAGRAM
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4 . TROUBLE SHOOTING CIRCUIT DIAGRAM KEY BACKLIGHT VBAT C318 1u C319 1u C320 1u C323 1u C321 1u C322 1u R344 47 R345 47 R346 47 R347 47 R348 47 R349 47 LEBB-S14H LD300 LD302 LD301 LEBB-S14H LEBB-S14H LD303 LEBB-S14H LD304 LD305 LEBB-S14H LEBB-S14H MIDI_KEY_BL1 MIDI_KEY_BL2 Checking Flow START NO Is the voltage level VBAT 3.6~4.2V? YES Charge battery Are all LEDs Working? NO Check the soldering each R and LED YES Backlight will work properly NO Replace or resoldering component - 77 -
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- 77 -
4 . TROUBLE SHOOTING
Checking Flow
START
Is the voltage level VBAT
3.6~4.2V?
Are all LEDs
Working?
Backlight will work properly
Replace or resoldering
component
Check the soldering
each R and LED
Charge battery
YES
NO
NO
NO
YES
CIRCUIT DIAGRAM
T
H
G
I
L
K
C
A
B
Y
E
K
H
4
1
S
-
B
B
E
L
5
0
3
D
L
u
1
9
1
3
C
7
4
8
4
3
R
7
4
7
4
3
R
6
4
3
R
7
4
9
4
3
R
7
4
7
4
5
4
3
R
4
0
3
D
L
H
4
1
S
-
B
B
E
L
T
A
B
V
2
2
3
C
u
1
u
1
3
2
3
C
H
4
1
S
-
B
B
E
L
0
0
3
D
L
0
2
3
C
u
1
1
2
3
C
u
1
8
1
3
C
u
1
H
4
1
S
-
B
B
E
L
3
0
3
D
L
4
4
3
R
7
4
1
0
3
D
L
H
4
1
S
-
B
B
E
L
H
4
1
S
-
B
B
E
L
2
0
3
D
L
2
L
B
_
Y
E
K
_
I
D
I
M
1
L
B
_
Y
E
K
_
I
D
I
M